1. Field of the Invention
The present invention relates to an automatic analyzer for performing qualitative/quantitative analysis of a biological sample such as blood and urine, and more particularly to an automatic analyzer that performs calculation by use of a calibration curve to obtain the result of analysis.
2. Description of the Related Art
Automatic analyzers for analyzing a biological sample such as blood and urine usually perform qualitative/quantitative analysis of a specific constituent contained in the sample by use of a reagent that reacts with the specific constituent. In particular, when the quantitative analysis is performed, in order to ensure the quantifiability, it is necessary to determine, as a calibration curve, the relationship between the absorbance, the emission intensity, or the turbidity, which is measured by the automatic analyzer, and the concentration by use of a sample whose concentration is known (this sample is called, for example, a “standard sample”). If a calibration curve is a straight line, the calibration curve is identified by a tilt and a y-intercept. Information used to identify such a calibration curve is designated as a “calibration curve factor”. When analysis is performed using an automatic analyzer, a calibration curve factor is determined by use of a standard sample before a general sample (patient sample) is analyzed.
There are several kinds of analysis methods including: analyzing one analysis item by use of only one reagent (analysis with one reagent); analyzing one analysis item by use of two kinds of reagents (analysis with two reagents); and analyzing one analysis item by use of three or more kinds of reagents. When one analysis item is analyzed by use of two or more kinds of reagents, a calibration curve is created for each set of reagent bottles (reagent set) used for the analysis.
As a reagent set management method, there are two kinds of methods: attaching, to each reagent bottle, an ID such as a bar code describing reagent information (a reagent code, a reagent production lot number, a reagent sequence number, the reagent expiration date, and the like) to manage reagent sets; and handling a set of reagent bottles as one cassette, and attaching, to each cassette, an ID such as a bar code describing reagent information to manage reagent sets.
The difference in reaction characteristics on a production lot basis and the change in reagent characteristics due to the time elapsed cause a difference in the result of measurement between reagents used for one analysis item. Accordingly, when a reagent whose production lot differs is newly registered in the automatic analyzer, or as time progresses, it is necessary to perform calibration again, and then to regenerate a calibration curve in a current reagent state.
For the difference in reaction characteristics on a reagent production lot basis, JP-A-08-262029 discloses an automatic analyzer that holds analysis conditions in a reagent bar code on a reagent lot basis so as to eliminate the difference in reaction characteristics between reagent production lots, and that is capable of performing correct sample analysis without key inputting.
For the deterioration of a reagent due to the time elapsed, JP-A-09-325150 discloses an automatic analyzer that corrects a change in the result of measurement due to the deterioration of a reagent, and a change in characteristics with time, at the time of calibration and measurement.
On the other hand, some conventional automatic analyzers have a function of enabling a user to directly input a calibration curve factor from a screen, or the like. For example, this function is used when an operator has no standard solution in hand, or when the operator directly inputs a calibration curve factor provided by a reagent manufacturer because a standard solution is expensive. In another case, this function is used when a calibration curve factor is corrected because characteristics of a reagent have changed. After the calibration curve factor is inputted, an accuracy control sample is analyzed to check the validity of the calibration curve factor. The validated calibration curve factor is used for measurement of a sample.
In this case, even in a state in which a plurality of reagent sets are placed in the automatic analyzer for the purpose of analyzing one analysis item, because the difference between reagent lots and the change in reagent characteristics cause the difference as described above, a calibration curve factor is always inputted on a reagent set basis, and the calibration curve factor is applied to only an appropriate reagent set, which is the actual situation.